Study protocol for the sheMATTERS study (iMproving cArdiovascular healTh in new moThERS): a randomized behavioral trial assessing the effect of a self-efficacy enhancing breastfeeding intervention on postpartum blood pressure and breastfeeding continuation in women with hypertensive disorders of pregnancy

Abstract

Background: Individuals with hypertensive disorders of pregnancy (HDP) have an elevated lifetime risk of chronic hypertension, metabolic syndrome, and premature cardiovascular disease. Because breastfeeding duration and exclusivity have been associated in observational studies with improved cardiovascular health, optimizing breastfeeding in those with HDP might be an unrealized cardio-prevention approach, in particular because individuals with HDP have more breastfeeding challenges. Breastfeeding supportive interventions targeting one's breastfeeding self-efficacy have been shown to improve breastfeeding rates.

Methods: We designed an open-label, multi-center 1:1 randomized behavioral trial to test whether a previously validated self-efficacy enhancing breastfeeding intervention can improve breastfeeding duration and/or exclusivity, and lower postpartum blood pressure at 12 months. Randomization is computer-generated and stratified by site (four hospitals in Montreal, Quebec and one hospital in Kingston, Ontario; all in Canada). Included are breastfeeding participants with HDP (chronic/gestational hypertension or preeclampsia) who delivered a live singleton infant at > 34 weeks, speak English or French, and have no contraindications to breastfeeding. Informed and written consent is obtained at hospitalization for delivery or a re-admission with hypertension within 1 week of discharge. Participants assigned to the intervention group receive a breastfeeding self-efficacy-based intervention delivered by a trained lactation consultant in hospital, with continued reactive/proactive support by phone or text message for up to 6 months postpartum. Regardless of group assignment, participants are followed for self-reported outcomes, automated office blood pressure, and home blood pressure at several time points with end of follow-up at 12 months.

Discussion: This study will assess whether an intensive nurse-led behavioral intervention can improve breastfeeding rates and, in turn, postpartum blood pressure - an early marker for atherosclerotic cardiovascular disease. If effective, this form of enhanced breastfeeding support, along with closer BP and metabolic surveillance, can be implemented broadly in individuals lactating after HDP.

Trial registration: ClinicalTrials.gov, # NCT04580927 , registered on Oct 9, 2020.

Keywords: Breastfeeding; Hypertensive disorders of pregnancy; Maternal health; Postpartum cardiovascular health; Self-efficacy.

Fig. 1

Hypothesized mechanism of cardiovascular protection of breastfeeding in women with hypertensive disorders of pregnancy. Conceptual diagram depicting associations between maternal hypertensive disorders of pregnancy and cardiovascular health, and hypothesized mediation by breastfeeding. Photos used in Fig. 1 were downloaded from iStock through a subscribed account. All photos have a Standard License, meaning we have the right to use the photos in perpetuity, and are referenced in Fig. 1

Fig. 2

Elevated Blood Pressure or Use of Anti Hypertensive Medication in Post Partum Women with HDP. This figure shows mean participant blood pressures according to study allocation group (breast feeding self-efficacy based intervention or usual postpartum care) at each of the study time points from the feasibility study “Breastfeeding and Blood pressure patterns in MOthers with hypertensive coMplications of pregnancy (BP-MOM)”. Elevated blood pressure was defined as average automated office blood pressure > 140/90 mmHg or average home blood pressure > 135/85 mmHg

Fig. 3

sheMATTERS Study Schemata. Schema of the sheMATTERS randomized behavioral trial design, additional comparison group, and long-term pragmatic cohort